Scaffold hoisting means



Feb. 7, 1967 Filed Oct. 26, 1954 C. H. ARNOLD SCAFFOLD HQISTING MEANS 4 Sheets-Sheet l Feb. 7, 1967 c. H. ARNOLD 3,302,750

SCAFFOLD HOISTING MEANS Filed Oct. 26, 1964 4 Sheets-Sheet 2 INVENTOR CARTE/P H. ,4R/VOM Feb. 7, C. H ARNOLD SCAFFOLD HOISTING MEANS 4 Sheets-Sheet 3 Filed Oct. 26, 1964 NVENTR. CARTE/ ARNOLD Feb. 7, 1967 c. H. ARNOLD 3,302,750

SCAFFOLD HOISTING MEANS Filed 001,. 26, 1954 4 SheGLS-Sheet 4 i i ,\l MFT (D www \f)\ i 'WN j (E 4 INVENTOR S CARTER ARA/OLD WM wm ATTORNEY United States Patent O "i 3,302,750 SCAFIFLD HUISTING MEANS Carter H. Arnold, Redwood City, Calif., assigner to Western Gear Corporation, Redwood City, Calif. Filed Oct. 26, 11964, Ser. No. 466,344 3 Claims. (Cl. HB2-12) This invention relates to scaffold hoisting me'ans and more particularly to an apparatus by which a scaffold or like support can be suspended from a structure so as to permit personnel on the support to work on the structure or for any other purpose.

The main object of the present invention is the provision of a novel hoisting means for a scaffold or staging which lends itself to use in instances where it is required to move the scaffold horizontally as well as vertically. The present invention is particularly adapted for use in the maintenance of the exterior of buildings and other structures since it provides means for moving a scaffold or staging supporting personnel vertically along the height of the structure or building and horizontally to different positions so that the personnel have access to the entire exterior of the structure.

Another object of the invention is the provision of a scaffold hoisting means that lends itself particularly to use with hoists of the type shown in Patent No. 2,917,272 dated December l5, 1959, and No. 3,063,653 dated November 13, 1962.

Another object of the invention is the provision of hoisting apparatus that can be employed as a permanent installation on a building at a relatively low cost compared with other permanent installations of like function.

Another object of the invention is the provision of a Wheeled carriage adapted to be used -with the hoisting apparatus that lends itself particularly for installation on the roof of a building in such a manner so as to permit the placement of a staging or scaffold at all points on the exterior of the building necessary to perform the various operations of maintenance such as washing windows, calking, painting and like operations.

Another object of the invention is the provision of a novel davit structure that facilitates the use of such davit and which permits the manual manipulation of a staging by the one or two persons normally employed on such staging or scaffold.

Still another object of the invention is the provision of a novel track arrangement land more specifically a juncture of a track that permits the wheeled carriages resting thereon to make a right angle turn within a minimum of space.

Another object of the invention is the provision of a scaffold hoisting means having a design lending itself to use on buildings of different types and contour Iand at the same time which hoisting means constitutes a permanent installation having optimum safety because it is securely connected to and actually becomes part of the building on which it operates.

Other objects and advantages of the invention will be apparent from the following specification and from the drawings wherein:

FIG. 1 is a perspective of the complete assembly contemplated by the invention showing the same making a turn around the track juncture.

FIG. 2 is a side elevational view of the apparatus of FIG. l showing the same supporting a scaffold or staging from the top of a building or other structure.

FIG. 3 is a fragmentary vertical cross sectional view partly in elevation showing the lower end of one of the davits and the davits bearings.

FIGA 4 is a fragmentary transverse sectional view taken in a plane indicated by lines 4 4 of FIG. 3.

Bddfld Patented Feb. 7, i967 FIG. 5 is 'a vertical cross section of one of the three casters of the davit carriage.

FIG. 6 is a fragmentary cross sectional View partly in elevation showing one end of the spreader bar that connects the two carriages.

FIG. 7 is a top plan view of a portion of the track structure showing the corner juncture and indicating schematically the method of forming the same.

Referring first to FIG. 1, the invention comprises generally a pair of davit structures generally indicated A and B between which a staging or scaffold C is suspended. The structures A and B may be considered to be identical in construction and for this reason only one will be described in detail. Each davit structure is adapted to support a hoist of the type shown in the above mentioned patents. Said hoists are indicated generally at D and E and function to support the scaffold in a manner to be described later on in greater detail.

Each davit structure is supported on a carriage generally designated lt] (FIG. 2) and including three casters generally designated lll which are mounted on a track consisting of rails 12, I3. With reference to FIGS. 1 and 2, it is seen that rail 1.2 is outboard relative to the building or other structure indicated at 1d while the rail 13 is nboard and generally parallel to rail l2. As best seen in FIG. 1, two casters of each carriage are provided on outer rail l2 and one caster on inner rail 113.

Each caster comprises a vertically disposed tubular housing It (FIG. 5) and the housings of each caster are secured together in xed spaced .apart relationship by means of a plurality of pipe members 19 (FIGS. 1, 2) thereby forming a unitary carriage supported at three points. As best seen in FIG. 5, each tubular housing 13 is provided with bearings for rotatably receiving therein a vertically extending shaft 19 provided at its upper end with a threaded cap 20 for xedly securing the shaft i9 relative to the upper bearing 2l. The shaft I9 extends downwardly past the lower bearing 22 and has xedly secured thereto, as by welding, a base generally designated 24. Base 24 is built up of flat plates welded together to form a unitary member. Rotatably supported in base 2d and directly below shaft I9 is a roller 253 which is adapted to roll on its corresponding rail l2 or 1.3.

The base 2d is also provided with four side rollers two of which, indicated at 26, engage one edge of the upper flange of the rail and are spaced apart longitudinally of said rail. The other pair 27 engage the opposite edge of the upper ange of the rail in a similar manner thus preventing more than a limited shifting of the caster laterally 0f the rail.

The caster is prevented from swinging upwardly relative to the associated rail by means of two pairs of lower rollers 28, 29 which engage under the upper ange of the associated rail as shown in FIG. 5.

At this point it will be noted that each caster structure is arranged to permit relative rotation between the tubular housing I8 and the base 2d so as to permit the carriage to turn a corner. Furthermore, the side rollers 26, 27 prevent lateral shifting of the caster beyond predetermined amounts relative to the rail, and lower rollers 2d, 29 prevent upward movement of the caster structure relative to the rail. It will be apparent from FIG. 1 that when the staging C is swung outwardly of the building I4, the inner caster tends to swing upwardly because of the moment yapplied to the associated davit structure; whereas when the staging C is swung inwardly relative to the building ld, the outer casters tend to swing upwardly. The caster structure of FIG. 5 thus provides adequate resistance to all types of loading applied to the device.

Each carriage 1l@ includes a vertically extending tubular housing 32 (FIG. 3) in which the lower end of the davit is rotatably mounted. Each of the davits A, B is essentially `an elongated length of steel tubing bent to provide a lower vertically extending portion 33 and an upper generally horizontal extending portion 34 (FIG. l).

The lower portion of each davit is rotatably supported `in a bearing 35 carried by the tubular housing 32. Spaced upwardly from the lower bearing 35 is an upper bearing 36 which is mounted in an enlarged sleeve 37 xedly secured as -by welding to the tubular housing 32. Adjacent the Iupper bearing 36 a reinforcing sleeve 411) is xedly secured to the dav-it. It is desirable not to permit the davits to rotate through a complete revolution and to this end a lug 41 (FIG. 4) is welded to sleeve 4d and extends radially outwardly therefrom. Said lug il is free to swing with the davit through an angle of about 270 and is prevented from swinging further by a radially inwardly extending projection t3 on a flange 42 formed at the yupper end of a relatively large sleeve da surrounding the sleeve 37 that is secured to the davit housing 32. Sleeve 44, is provided at its lower end with a plurality of. downwardly opening recesses 45 which are adapted to receive therein radially outwardly extending bolts 46 fixedly .secured to sleeve 37.

One of the important 4features of the present invention is the provision of means to facilitate the swinging of the staging C from an outer to an linner position and vice versa without the intervention of any means except the manipulation of the staging by the personnel thereon. The steps in t-he operation of s-winging a staging (or a lifeboat) from outboard to inboard positions and vice versa by means of dav-its are well understood. Briefly, such steps require that one davit be swung first to swing one end of the load and then the other davit is swung to swing the other end of the load. By the present invention this operation is facilitated by means of a fixed handwheel 47 which surrounds the davit at a point adjacent the juncture between the vertically extending portion 33 and the horizontally extending portion 34 (see FIG. l). Each handwheel 47 is secured to the upper ends of a plurality of pipe members d3 which, as best seen in FIG. 2, extend vertically at their lower ends at points radially outwardly of the vertical section of the davit and are curved at their upper ends so as to connect with the handwheel 47. The pipe members 48 :may be conveniently joined together as by rwelding to an annular plate i9 adjacent but spaced upwardly from the lower ends of the members 4S. The extreme lower ends of the members 48 may then be received within tubular sockets 50 which in turn are tixedly secured as by welding to the sleeve 44 which in turn is xed relative to the stationary davit housing by means of bolts 46. By this structure it will be seen that the handwheel t7 is fixed relative to its associated davit so that personnel on the staging may grasp the handwheel and, by pushing or pulling as the case may be, swing the staging as required to effect a change of position from outboard to inboard and Vice versa. If the handwheels t7 were not provided it would be necessary for additional personnel to assist Iin the swinging of the staging or it would be necessary lfor the personnel on the staging to get off the staging and manipulate the later from the structure.

Another important feature of the invention is the provision of two identical carriages l which are interconnected so that each may be employed separately, if desired, for example if it is desired to lower a bosns chair from the structure .such as -indicated at lid, In furtherance of this object the two-wheeled carriages l0 are releasably connected together by means of a spreader bar generally designated l (FIGS. l, 6). This spreader bar is connected at -its ends to lugs 52 welded to the tubular housings 18 that are closest to each other and which housings are in enga-gement with the outer rail l2. The opposite ends of spreader bar 5l are provided with pins 53 received through corresponding holes in lugs 52 so that said spreader bar 5l -is swingably connected relative to the carriages that it connects. Preferably, the spreader bar '5l is provided with end sections 54, 55 telescopically received within a central section 56 and tixedly secured to .said central section as by bolts 57. I-f it is desired to change the spacing between the carriages l0 it is therefore a simple matter to reduce or expand the effective length of spreader bar 51.

The struct-ure that comprises the pair of `spaced apart wheeled carriages swin-gably connected to the elongated spreader bar lends itself to `use in the maintenance of most buildings by reason of the fact that the structure permits a relatively sharp turn to be made by the carriages at a corner of a building. Thus, as seen in FIG. 7, the track which consists of outer land inner rails 12, i3 may include elongated track sections as indicated with said sections in perpendicularly intersecting relationship and joined together by a curved juncture generally indicated at 6). Said juncture comprises an outer .section 61 which is in the form of a circular arc tangent at its ends to the straight portions of rail 12. The inner section of juncture 6o that connects with straight sections of the inner rail 13 is indicated at 62. This inner section 62 has an unusual shape in that it does not conform to any particular curve but may be defined as the locus of all points assumed by the inner caster that engages inner rail 13 as the outer casters proceed around the outer ection 61 which is in the form lof a circula-r arc. The inner section 62 may be laid out by plotting the various positions which the inner caster takes as the outer casters proceed around the section 6l. This layout may be made by use of a template defining the carriage and indicated in FIG. 7 at 63. If it were not for the shape of juncture 6d as above described it would be impossible for an elongated wheeled member that is suiiiciently long to accommodate the staging C to proceed around a corner without the use of switching means on the track or without the use of a very large juncture which would not only reduce the usable space left on the top of a building or other structure but would also prevent the staging C from approaching closely enough to the corners of the building to permit the entire building to be covered. It should be noted that the movable structure that include the two carriages pivotally connected by the spreader bar 5l constributes to the effective design of the track described above.

Referring now to the actual hoisting mechanism, each davit A, B is provided at the outer end of its horizontally disposed section 35 with hoisting lugs 67 to which is `secured the relatively flexible hoisting cable 65 on which the hoist D or E operates. Said .hoists D and yE are fully described -in the above `mentioned patents and are not described in detail herein; however, it should be noted that the operation of said hoists is such that they move along the length of the hoisting cable 63 and do not windup on a drum as in older conventional hoisting equipment. Each hoisting cable 68 is thus provided with a slack end 68 extending downwardly from the hoist. So as not to cause fouling of said lower slack end 68 with other objects it is desirable to employ a rope coiling apparatus generally indicated at `69 and of the type disclosed in patent application Serial No. 283,465 led May 27, 1963. The behavior of the lower slack end of the cable indicated at 63 is the same with the use of the coiling device 69 as it would be if the slack end of the rope 68 were simply suspended from the hoist; in other words, there is no resistance of any appreciable amount on the cable while the sa-me is being moved tinto and 4out of the coiling device 69.

Although the hoists D, E may be operated by air, the type driven by electric motor is shown in the drawings. The wires to said motor may be led first into a control box 9d, then upwardly along the inside of davit B to a cable cage generally indicated at 70 from which leads 7l, 72 may be connected to the respective hoists.

Another of the important advantages of the present invention resides in the safety feature that is achieved by the provision of a safety line indicated at 75 in FIGS. l and 2 and which line is connected at its upper end to lugs 74 at the outer end of the davit in a similar `manner to line 68. However, it should be noted that the safety line 75, not bein-g required to be wrapped around a relatively small drum, `may be less flexible than the hoisting cable 68. The lower end of the fixed safety line 75 may conveniently be passed through a suitable opening in the central shaft of the coiling device 69 and downwardly through the floor 76 of the staging C and into another coiling device similar to coiling device 69 and which is indicated at 77. The hoists D, E are connected to the stagving C for supporting the latter by means of stirrups `generally designated 78 and which stirrups are connected at their upper ends to a depending plate 79 on the hoists D, E. The safety line 75 is passed through a cable gripping device generally designated 80 (FIG. 2) and which device is conventional in that means is provided for gripping the rope passed therethrough when a switch associated with the device is opened or closed as the case may be. Said gripping device 80 may be secured to a supporting plate 81 which in turn may be fixedly secured to the stirrup 78. As will be more apparent later on, upon failure of the hoisting device the gripping device 80 isl actuated so that the same grips the rope preventing further movement of the scaffold relative to the safety `line 75.

There are several methods of actuating gripping device.

80 and the one method contemplated `herein is through the provision of a switching means on the hoisting rope 68 and which switching means is adapted to be actuated when the tension in the rope 68 becomes less or greater than a predetermined range. The switching means disclosed herein is conventional and no claim is made to the same except in combination with the other features of the invention. Said conventional switching means may be of the type that includes a U-shaped member 83 to the legs of which are attached eyes 84, 85 (FIG. 2) which in turn are connected to the davit and to the hoisting rope 68. The switching device 83 is within an electrical circuit (not shown) which includes the gripping device 80 `so that if the rope 68 slips with respect to the associated hoist thereby reducing the tension in rope 68 lor if the scaffold is overloaded and causes excessive tension the` safety line 75 automatically takes the weight of the scaffold through the gripping device 8f).

It is advantageous to be able to move the carriages 10 under the control of the personnel on the staging C without requiring such personnel to get out of the staging. To this end one carriage is provided with a conventional friction drive generally designated 88 which is run by an electric :motor and which 4drive includes a large friction wheel 90 in engagement with the upper ange of rail 12. Power may be supplied to the motor of driving unit 88 from control box 94 and actuation of said motor may be effected by a relay actuated from a switch box 93 at the outer end of davit B. By providing the switch box at the outer end of the ldavit it will be apparent that the carriages 10 cannot be moved until a person on staging C actuates said switch 93 and which actuation can only be carried out when the staging C is up above the level of the rails 12, 13. This prevents dangerous swinging of the staging that mi-ght otherwise occur if the carriages 10 were inadvertently moved by one on top of the building while the staging is suspended a relatively great distance below the davits.

It' will be apparent that the apparatus described herein lends itself to incorporation of other safety features. For example the power line to the driving unit 88 may be provided with an interlock requiring the hoists to be in their uppermost position relative to the davits before the motor of the driving unit 88 may be energized.

To facilitate positioning the apparatus at various predetermined .positions relative to the .structure in order to permit the personnel on staging C to adequately cover the entire structure cam-ming ramps 96 are formed on the lower ange of outer rail 12 so as to actuate a switch generally designated 97 carried by carriage 16. Upon engagement with one of the camming ramps 96 switch 97 opens the circuit of drive unit 88 and automatically stops the apparatus at the next desired position. Switch box 93 may be provided with a by-pass control as well as left and right controls to permit the carriage to be moved despite the actuation of switch 97.

It will be seen that the above described invention lends itself to use on both new and existing buildings and provides a relatively inexpensive means for supporting personnel at any point on the exterior of a building. Such personnel are enabled to reach the corners of the building because, if required, the staging C may Abe lowered even when one of the carriages 10 is on the juncture 60 of the track. In such a case, by swinging the corner davit outwardly to a -greater extent than the other davit, the staging C `may -be brought closely adjacent the corner of the building.

Unlike most building maintenance installations, the present invention does not require. custom building of the hoisting means but rather lends itself to use with almost any type of structure regardless of contour orconstruction.

Although power means has been shown for moving the installation from one drop to another, it will be understood that such ymovement may be effected manually, if desired, thereby achieving a saving in cost. In such a case it is contemplated that Amechanical stops may be provided for automatically stopping the carriages at predetermined positions to permit complete coverage of the building.

In addition to the above noted safety features it will be seen that the carriages are permanently secured to the structure against disconnection therefrom and even if rollers 28, 29 on bases 24 were to fail the hook-shaped plates which support them and which are integral with said bases would prevent complete detachment from the rails which in turn are fixedly secured to the building.

The safety line is extremely desirable for promotion of optimum safety. However, the particular switching -means shown may take other forms and be located differently. For example, the present invention also contemplates the use of a conventional centrifugal type of switching means which actuates the -gripping device when the speed of the scaffold relative to the rope exceeds a predetermined amount.

The switching means 83 `shown adjacent the outer end of the davit may be positioned between the hoist E or D and the associated stirrup; in such a case the by-pass, usually incorporated in such switching devices, may be operated regardless of the position of the scaffold.

As an extra safety feat-ure the safety line 75 may be continued downwardly through the davit to the carriage so as to hold the scaffold even if the davit fails completely.

The above specific description of the preferred form of the invention should not be taken. as restrictive as it will be apparent that various modifications in design may be resorted to without departing from the scope of the following claims.

I claim:

1. Hoisting apparatus comprising:

a supporting member adapted to be positioned at an elevated point relative to a structure,

a first rope secured at its upperl end to said member and depending therefrom,

a hoisting unit secured to said firs-t rope for moving an associated load vertically along the length of said first rope,

a second rope secured at its upper end to said member and depending therefrom,

gripping means coacting between said load and said second rope for gripping said rope to hold said load against movement relative to said second rope,

sensing means carried by said first rope for sensing the tension therein,

:means operatively connecting said sensing means and said gripping means for automatically actuating the latter to hold said load on said second rope when 4the Itension on said first rope is above or below a predetermined range.

2. Davit structure comprising:

a base,

a davit having a vertically extending lower end and a generally horizontally extending upper end,

bearing means on said base for oscillatably supporting said lower end to permit swinging said davit about a vertical axis,

an extension fixed at its lower end to said base and extending upwardly therefrom and terminating at its upper end in a portion positioned radially outwardly of said lower end,

said upper end of said davit being provided with means for supporting a load such as a scaffold,

said portion of said extension being adapted to be grasped by a hand of a person on said load to permit swinging said davit about said axis.

3. A structure according to claim 2 wherein said portion comprises a ring concentric with said axis and xedly secured to said extension.

References Cited by the Examiner UNITED STATES PATENTS 724,627 4/1903 Swegle 104-149 1,699,544 1/1929 Rohlfng 182-14 2,600,199 6/1952 Brewster 182--142 X 2,662,734 12/1953 Allenbaugh 182-142 2,684,039 7/1954 King 104-88 2,881,029 4/1959 Tollefsen 182-14 2,939,550 6/1960 Puttle 182-142 3,130,813 4/19 64 Fackler 182-36 3,159,110 12/1964 Wylie 104-246 FOREIGN PATENTS 319,480 4/1957 Switzerland.

REINALDO P. MACHADO, Primary Examiner. 

1. HOISTING APPARATUS COMPRISING: A SUPPORTING MEMBER ADAPTED TO BE POSITIONED AT AN ELEVATED POINT RELATIVE TO A STRUCTURE, A FIRST ROPE SECURED AT ITS UPPER END OF SAID MEMBER AND DEPENDING THEREFROM, A HOISTING UNIT SECURED TO SAID FIRST ROPE FOR MOVING AN ASSOCIATED LOAD VERTICALLY ALONG THE LENGTH OF SAID FIRST ROPE, A SECOND ROPE SECURED AT ITS UPPER END TO SAID MEMBER AND DEPENDING THEREFROM, GRIPPING MEANS COACTING BETWEEN SAID LOAD AND SAID SECOND ROPE FOR GRIPPING SAID ROPE TO HOLD SAID LOAD AGAINST MOVEMENT RELATIVE TO SAID SECOND ROPE, SENSING MEANS CARRIED BY SAID FIRST ROPE FOR SENSING THE TENSION THEREIN, MEANS OPERATIVELY CONNECTING SENSING MEANS AND SAID GRIPPING MEANS FOR AUTOMATICALLY ACTUATING THE 